Although the autogenous saphenous vein is the vessel typically utilized in arterial bypass procedures, occasions arise in which it is not possible to use this vein, demanding an alternative method. The investigators propose a feasibility study in canine subjects to determine whether an immunologically modified xenogeneic vessel with recipient endothelium can serve as a replacement of the autogenous saphenous vein. The investigators intend to assess the viability of the tissue modification technique, and seek to optimize endothelial cell seeding. The final object of this effort will be to assess in vivo the biocompatibility of the implant, as well as its overall effectiveness as a graft.